Between 1985 and 1996 all patients seen consecutively in my private practice who were undergoing surgery for intermittent exotropia, and in whom the near deviation was within 10 prism diopters (Δ) of the distance deviation (prior to monocular occlusion or the use of +3 lenses at near) were included in this study subject to the following exclusion criteria: untreated or unsuccessfully treated amblyopia, the presence of an A or V pattern requiring treatment, simultaneous oblique muscle surgery, lateral incomitance of more than 10Δ,15,16 history of previous strabismus surgery, the use of adjustable sutures, follow-up of less than 1 year, insufficient cooperation for the above-mentioned measurements, or unwillingness to be randomized. Because I wanted to limit this study to patients in whom accurate measurements could be obtained with the prism and alternate cover test, the lower age for inclusion was 3 years. Also, because I frequently use adjustable sutures on postadolescent patients and because I wished to eliminate the confounding variable that would be introduced by the use of adjustable sutures, I set the upper age limit for inclusion at 18 years. In addition, patients were excluded if I knew at the time of surgery that their follow-up would be carried out by the referring physician. I considered patients to have intermittent exotropia if their deviation was intermittently manifest at either distance or near. Consequently, I included patients who had a constant exotropia at distance but an intermittent exotropia at near. Randomization to 1 of 2 groups occurred when each patient was scheduled for surgery and after I obtained informed consent. One group, referred to as the "recess/resect group," underwent a recession of the lateral rectus and a resection of the medial rectus of the nondominant eye. The second group, referred to as the "lateral rectus recession group," underwent symmetric lateral rectus recessions. For both groups, surgery was based on the measurement obtained at 6 m with appropriate optical correction in place and prior to monocular occlusion. If patients had been treated with minus lens therapy or base-in prism prior to surgery, they were put in their appropriate cycloplegic spectacle correction without prism; it was with those spectacles that the measurements for this study were obtained. For myopic patients, the full cycloplegic refraction was dispensed. For hyperopic patients, spectacles were prescribed if there was any substantial astigmatic refractive error, anisometropia greater than one half diopter (D), or hyperopia greater than 2 D. In most cases, patients with hyperopic intermittent exotropia were given spectacles that incorporated approximately 1 to 1 D less than the full cycloplegic hyperopic refraction. Outcome determination was made at the earliest examination date performed at least 1 year after surgery (range, 12-15 months). An outcome was considered satisfactory if there was between 10Δ of exophoria and 5Δ of esophoria. An intermittent or manifest tropia of any amount, either exotropic or esotropic, was considered an unsatisfactory outcome. Patients who underwent a reoperation, who needed prisms after surgery, or who needed manipulation of their accommodation with plus or minus lenses to meet the aforementioned criteria were considered to have an unsatisfactory outcome. Table 1 gives the popular surgical formula that was used for both groups.10 In addition, any patients in whom the angle of exotropia at 6 m increased after 1 hour of monocular occlusion or while looking out a window at a far distant target were excluded from this study because they were the subject of a simultaneously conducted, different randomized clinical trial (see "Comment" section for significance of this exclusion).17 The outcome measurements were not masked.